Print slug mounting means in type chain assembly

ABSTRACT

A chain printer having a type chain which comprises an endless flexible belt to which a plurality of abutting print slugs are attached. Each print slug contains a printing portion located on the outside of the belt and a pair of driving portions which are cantilevered from the printing portion and project across the belt&#39;&#39;s edges. Type characters are located on the printing portions and the driving portions have their cantilevered ends shaped to mesh with peripherally spaced notches in a driving pulley so that they thereby drivingly engage the chain with the pulley. Preferably, the pulley is made up of three parts: top and bottom parts having peripherally spaced notches, and a center part which projects between the slugs&#39;&#39; driving portions and abuts the inside of the belt when the type chain moves around the pulley. In addition, preferably, the outside of the belt is toothed and each slug&#39;&#39;s printing portion contains a slot into which one of the teeth tightly projects.

United States atent [72] Inventor James H. Edwards Winchester, Mass.

Sept. 30, 1969 Jan. 1 1, 1972 Mohawk Data Sciences CorporationI-Ierkimer, N.Y.

[21 Appl. No. [22] Filed [45] Patented [73] Assignee [54] PRINT SLUGMOUNTING MEANS IN TYPE CHAIN ASSEMBLY 5 Claims, 6 Drawing Figs. [52]U.S.Cl. 101/111 [51] Int. Cl. B411 1/20 [50] Field of Search 101/93 C,

93 MN, 96,111,109, 368, 383, 93 R Primary Examiner-William B. PennAttorneys-Francis .1. Thomas, Richard H. Smith, Thomas C. Siekman andSughrue, Rothwell, Mion, Zinn &

MacPeak ABSTRACT: A chain printer having a type chain which comprises anendless flexible hell to which a plurality of abutting print slugs areattached. Each print slug contains a printing portion located on theoutside ofthe belt and a pair of driving portions which are cantileveredfrom the printing portion and project across the belts edges. Typecharacters are located on the printing portions and the driving portionshave their cantilevered ends shaped to mesh with peripherally spacednotches in a driving pulley so that they thereby drivingly engage thechain with the pulley. Preferably, the pulley is made up of three parts:top and bottom parts having peripherally spaced notches, and a centerpart which projects between the slugs driving portions and abuts theinside of the belt when the type chain moves around the pulley. Inaddition, preferably, the outside of the belt is toothed and each slugsprinting portion contains a slot into which one of the teeth tightlyprojects.

PATENTED JAN] 1 I972 SHEET 1 [IF 4 FIG! ATTOR N EY PATENTEU JAN? 1 I972SHEET 3 BF 4 MOE PRINT SLUG MOUNTING MEANS IN TYPE CHAIN ASSEMBLYBACKGROUND OF THE INVENTION This invention relates to chain printersand, more particularly, to the type chain in such a printer.

Printers have been developed in which a type chain containing typecharacters on a continuous chain of print slugs is moved along the printline across the document being printed upon. In these printers, commonlycalled chain printers, one or more hammers adjacent the print lineselectively strike the document against the moving type characters whichpass on the back side of the document. The type chain moves around apair of spaced-apart pulleys which contain peripherally spaced notchesfor engaging the chain. One of the pulleys is driven to move the chainacross the document.

The type chain in some printers comprises flexible endless belt to whichthe print slugs are attached. Spaced teeth are located on the inside ofthe belt and the chain is moved by a driving engagement between theseteeth and the notches in the driving pulley. Other chain printersutilize a type chain made up only of abutting print slugs which movealong a raceway; each slug contains teeth for engaging the drivingpulley which thereby rnoves'the chain.

Both these type chains have drawbacks. In the former, since the chainengages the pulleys via the belt, some of the energy imparted to thechain when the hammers strike the document against it is transmittedalong the belt to the pulleys. Because of the belts elasticity, suchenergy transfer causes vibrations in the chain.

The second type chain avoids this problem by omitting the belt andtransmitting the hammers energy to the pulleys via the nonelasticabutting slugs. However, it is difficult to stabilize the positions ofthe slugs within a chain made up of unconnected slugs. In addition,since hammer impact on a slug has a braking effect on the struck slug,this chain design allows a gap to occur between the struck slug and theone which is moving ahead of it in the chain. Therefore, since it isnecessary that the slugs be precisely positioned and tightly held withinthe chain to enable the hammers to strike the proper type characters atthe exact time, this chain has inherent drawbacks.

SUMMARY OF THE INVENTION It is, therefore, the primary object of thisinvention to provide a chain printer having a type chain which avoidsthe disadvantages of both of the above type chains and yet is economicalto manufacture and maintain.

In accordance with the invention, there is provided a type chain adaptedto be drivingly engaged by a peripherally notched driving pulley whichmoves the chain across the document. The type chain comprises a belt towhich a plurality of print slugs are attached. Each slug contains aprinting portion having type characters thereon and at least one drivingportion which has an end shaped to mesh with the notches in the pulleyto drivingly engage the chain and pulley. In the preferred embodiment,each slug has its printing portion located on one side of the belt andits two driving portions cantilevered from the printing portion andprojecting across opposite edges of the belt. The cantilevered ends ofthese driving portions are shaped to engage the pulley.

Preferably, the belt is a standard low-cost endless timing belt havingone toothed side. The toothed side is located adjacent the slugsprinting portions, each of which contains a slot into which a toothtightly fits so that the slugs are maintained in place within the chain.

Also in the preferred embodiment, the driving pulley is made up of threeparts; top and bottom parts containing peripheral notches, and a centralpart which is adapted to project between the slugs driving portions andabut the belt as the type chain moves around the pulley.

Since the chain engages the pulleys via the print slugs and not thebelt, the energy imparted to it by the hammer is transmitted to thepulleys by the slugs and not the elastic belt. However, the print slugsare securely held in place by the belt and, thus, a stable chain isprovided.

Also, preferably, adjacent slugs within the chain abut. This furtherreduces vibrations within the chain by allowing energy from hammerimpact to be transmitted along the abutting slugs to the pulleys.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic perspective viewof a preferred embodiment of the printer.

FIGS. 2 and 2a are perspective views of two print slugs attached to thebelt.

FIG. 3 is a plan view, partly sectioned, showing the driving pulleyengaging the type chain.

FIGS. 4 and 5 are sections taken along lines 44 and 55 in FIG. 3respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 schematically shows achain printer printing on a document 1 which is stepped upwardly by apair of tractors, 2 and 3, engaging edge perforations 1a in thedocument. The printer includes a plurality of hammer mechanisms disposedalong the print line, i.e., that line along which characters are beingprinted. Each hammer mechanism contains a hammer 4a which, whenactivated by an electromagnet 4b, moves about a pivot 4c. One or morefonts of type characters are moved along the print line adjacent thehammers 4a by a type chain moving at a constant speed in a fixedcontinuous path. The type chain comprises a plurality of print slugs 5on which the type characters are located, and an endless flexible belt 6(FIG. 2) on which the slugs are secured. During the printing operation,selected hammers impact an inked ribbon 7 and a document 1 againstselected type characters on the slugs 5. The inked ribbon is locatedbetween the document 1 and the type chain, and is fed from a supplyspool onto a takeup spool 8b.

The type chain continuously travels around a pair of pulleys: an idlerpulley 9a and a driving pulley 9 which is driven by means not shownlocated within a printer support 10. A conventional code disk 11 ismounted on the shaft 12 of the driving pulley 9. It contains a pluralityof radial slots which represent the rotating type characters and afurther slot for indicating the end of each font. Light from a lightsource 13 is directed onto the code disk and passes through slotstherein and onto a photosensitive unit 14. By this well-knownarrangement, the photosensing unit produces electrical outputsrepresenting the positions of the type characters in the moving typechain. Such electrical signals are then used to properly time theactivation of the hammer mechanisms.

As illustrated in FIG. 2, each print slug 5 has two type characters 15thereon. By using a plurality of type characters on each slug, theprinting speed may be increased with respect to the speed of the typechain. The type characters are located equidistant from the top andbottom of the slugs so that the hammers do not tend to overturn theslugs when providing impact between the type characters and document.

As shown in FIGS. 2 and 2a, each printing slug is essentiallychannel-shaped and made up of a printing portion 16 and upper and lowerdriving portions 17. The printing portion abuts the outside 6a of theendless belt 6 and has the type characters 15 thereon. The belt isformed from fiberglass-reinforced neoprene and is of a type currentlymanufactured by the United states Rubber Company as a timing belt. Thetoothed outside of the belt abuts the printing portions 16 of the printslugs 5 with each print slug containing a centrally located slot 19(FIG. 3) into which a tooth 18 of the belt projects and tightly fits. Inthis manner, the print slugs are precisely positioned at fixed locationsalong the belt within the type chain. Because of its elasticity, eachtooth also serves to dampen hammer impact on the slug.

As best illustrated in FIGS. 2a and 4, each slugs driving portions 17,after projecting across the edges of the belt 6, contain ears 20 whichextend substantially parallel to the printing portion 16 of the slug onthe outside 6a of the belt. These ears abut the inside 6b of the beltand clamp the belt against the printing portion of the slug. in thismanner, each slug is securely attached to the belt.

Referring to H68. 3 and 4, the type chain is illustrated in drivingengagement with the driving pulley 9. The pulley contains notches 30equally spaced around its periphery. The driving portions 17 of theslugs have their cantilevered ends 17a, i.e., those ends away from theslugs printing portions, shaped to mesh with the peripheral notches 30.A driving connection is thus set up between the pulley and type chain asthe chain moves around the pulley. In the preferred embodimentillustrated, the cantilevered ends 170 of the driving portions and thenotches 30 in the pulley are approximately trapezoidal.

As best shown in FIG. 4, the driving pulley 9 is made up of three parts:top and bottom parts, 21 and 22, which contain the peripherally spacednotches 30, and a central part 23 interposed between the top and bottomparts. In effect, the top and bottom parts are circular gears. Thecentral part is adapted to project between the cantilevered ends 17a andcars 20 of the driving portions of the slugs when the type chain movesaround the pulley. The central part 23 of the pulley abuts the inside 6bof the belt and fits tightly between the ears 20. Of course, the idlerpulley 9a around which the type chain also travels is constructedsubstantially identical to the driving pulley. With sufficient tensionmaintained in the type chain, the chain is effectively guided in itscontinuous path by cooperation between the central parts 23 of thepulleys and the ears 20 of the driving portions of the slugs.

Since the slugs constitute that part of the type chain which engages thepulleys, the energy from hammer impact on the chain is transmittedthrough them to the pulleys. The connection between the chain andpulleys involves only nonelastic elements and not the elastic belt. Thisreduces vibrations within the chain. Preferably, as illustrated in FIG.3, adjacent slugs in the chain abut. This feature also reduces chainvibrations as energy transfer from hammer impact is along abutting slugsto the pulleys.

FIGS. 1, 3 and show an impact resisting member 24 disposed between thepulleys 9 and 9b and between the type chain. It is an essentially flatmember having concave ends which adjoin the driving and idler pulleys.The impact resisting member is located adjacent the print line andprovides the backstop necessary to resist the impact from the hammers 4aas they force the document against the inked ribbon 7 and typecharacters on the slugs 5. The hammers return to their initial restpositions by rebounding from the slugs 5 and the impact resisting member24. When a hammer is operated to strike a type character on a slug, thecantilevered ends 17a of that slugs driving portions 17 are forcedagainst the impact resisting member. However, when they are not beingforced together, a slight clearance is provided between the impactresisting member and the print slugs to reduce noise and frictron.

FIGS. 3 and 5 also show a stop member 25 secured adjacent the print lineto the impact resisting member with screws 26. The stop member has a lip27 extending parallel to the print line and placed adjacent that side ofthe slugs printing portions 16 having the type characters 15 thereon.With this arrangement, the stop member 25 prohibits the print slugs fromrebounding an unsatisfactory distance away from the impact resistingmember 24 after the slugs are impacted by the hammers. As with theimpacting resisting member, clearance is provided between the stopmember and the slugs, thus reducing noise and friction.

I claim:

I. A type chain assembly comprising:

a. a driving pulley having notches spaced around its periphery;

b. an endless flexible belt adapted to move in a continuous path atleast part of which is around the pulley; c. a plurality of abuttingprint slugs arranged along the length of the belt, each slug having aprinting portion with at least one type character thereon adjacent theoutside of the belt, each slug also having a pair of cantileveredportions projecting from its printing portion and across opposite edgesof the belt, the cantilevered ends of each pair of cantilevered portionsbeing shaped to mesh with the notches in the pulley to drivingly engagethe slugs and pulley; and

d. a pair of ears on each of the slugs, each pair of ears projectingfrom the cantilevered portions of its associated slug and abutting theinside of the belt to clamp the belt between itself and the slugsprinting portion.

2. The type chain assembly as recited in claim 1 further comprising aseries of spaced teeth located on the outside of the belt, and whereinthe printing portion of each slug con tains a slot into which one of theteeth projects.

3. The type chain assembly as recited in claim 2 wherein each slot iscentrally located within its printing portion and each tooth tightlyfits into the slot into which it projects.

4. The type chain assembly as recited in claim 2 wherein each pair ofears abut the inside of the belt at a location along the belt where oneof the teeth is located on the outside of the belt.

5. The type chain assembly as recited in claim 1 wherein the pulleycomprises top and bottom parts which contain peripherally spacednotches, and a central part interposed between the top and bottom parts,the central part of the pulley adapted to project between the ears ofthe slugs when the slugs move past the pulley.

1. A type chain assembly comprising: a. a driving pulley having notches spaced around its periphery; b. an endless flexible belt adapted to move in a continuous path, at least part of which is around the pulley; c. a plurality of abutting print slugs arranged along the length of the belt, each slug having a printing portion with at least one type character thereon adjacent the outside of the belt, each slug also having a pair of cantilevered portions projecting from its printing portion and across opposite edges of the belt, the cantilevered ends of each pair of cantilevered portions being shaped to mesh with the notches in the pulley to drivingly engage the slugs and pulley; and d. a pair of ears on each of the slugs, each pair of ears projecting from the cantilevered portions of its associated slug and abutting the inside of the belt to clamp the belt between itself and the slug''s printing portion.
 2. The type chain assembly as recited in claim 1 further comprising a series of spaced teeth located on the outside of the belt, and wherein the printing portion of each slug contains a slot into which one of the teeth projects.
 3. The type chain assembly as recited in claim 2 wherein each slot is centrally located within its printing portion and each tooth tightly fits into the slot into which it projects.
 4. The type chain assembly as recited in claim 2 wherein each pair of ears abut the inside of the belt at a location along the belt where one of the teeth is located on the outside of the belt.
 5. The type chain assembly as recited in claim 1 wherein the pulley comprises top and bottom parts which contain peripherally spaced notches, and a central part interposed between the top and bottom parts, the central part of the pulley adapted to project between the ears of the slugs when the slugs move past the pulley. 